Myopia Manual

In general, the earlier the myopia appears, the higher are the D values it will reach⁶. But on the other hand, as stated by Goldschmidt⁵⁵ "myopia progression can stop at any time transiently or permanently". This statement, based on experience of optometrists and ophthalmologists, shows how shaky the overall knowledge of myopia development still is.

Independent of myopia, it was found that "There was a significant correlation of scleral stiffness with age …"⁵⁶, which gives some hope to myopic people, because the increasing rigidity results in less axial growth or even in a standstill of growth.

1.9 Accommodation and Age

The average power of accommodation, of which the eye is capable, depends on age:

D stands for diopters. This dimension equals to the reciprocal value of the focal distance of a lens (see section 1.11).

This process of a diminishing of accommodation is called presbyopia.

Consequently, almost everybody has to wear glasses or contact lenses during a more or less extended period in life. An older person with moderate myopia can often read by simply taking the glasses off. And for wearers of contact lenses there is the chance to wear bifocal contact lenses. This is a reason to avoid corrective surgery.

The graphical presentation of this mechanism is shown in Figure 4.

Figure 4: The change of accommodation amplitude with age

Figure 5: The accommodation effort with respect to age and effort.

Figure 5 is a somehow different representation of the relation between the accommodation effort and the distance for which proper focusing can be achieved with increasing age. Even emmetropic persons need glasses to cover the range from reading distance to distant focus. Their glasses have to take care of the reading distance, the myopes's have to take care of the long distance.

It has been claimed that only very few non-myopic people over 60 are still able to accommodate, and it was concluded from research that a hotter climate accelerated the decrease in accommodative power¹⁶.

Note:
Quite frequently older people report that their myopia is decreasing, attributing this to presbyopia. The reason, however, might be as well a beginning of diabetes, which changes the refractive power of the lens (see section 3.16.1).

1.10 Some more Age Related Geometrical Changes of the Eye

The anterior chamber decreases after the age of 20 because the lens is thickening. There appear to, be, however, variations depending on ethnicity. Whether this thickening is happening for men and women in the same way is disputed¹⁶.

A study⁵⁷ with non-myopic children between age 6 and age 16 in Tibet showed:

It was concluded in this study by Garner et al.⁵⁷, "that the balance between the decrease in crystalline lens power and the increase in vitreous length is the major factor in maintaining the tendency to emmetropia in these children."

Note:
According to these results a disturbance in the described reduction of the lens power might already contribute to the appearing of myopia.

Contact Us